Absorption refrigeration apparatus



June 10, 1952 w KQGEL 2,599,562

ABSORPTION REFRIGERATION APPARATUS Filed NOV. 26, 1947 2 SHEETS-SHEET 13'0 NVENTOR.

[ah 4770mm? by vapor-liquid lift action through pipe 28 into the upperpart of boiler iii. Refrigerant vapor expelled out of solution in boilerit, together with refrigerant vapor entering through pipe 28, flowsupwardly from the vapor expulsion unit 3 to the condenser I4, aspreviously explained. The absorption liquid from which refrigerant vaporhas been expelled flows from the boiler [3 through the outer pipe orpassage 3% of liquid heat exchanger 2! and conduit 23 into the upperpart of absorber coil 22. The circulation of absorption solution in theliquid circuit just described is eifected by raising of liquid throughpipe 23.

The outlet end of condenser I4 is connected by an upper extension ofconduit l5, vessel 3! and conduit 32 to a part of the gas circuit, as atone end of heat exchanger 19, for example, so that any inert gas whichmay pass through the condenser M can flow into the gas circuit.Refrigerant vapor not liquified in the condenser flows through the upperpart of conduit l5 to displace inert gas in vessel 3| and force such gasinto the gas circuit. The effect of forcing gas into the gas circuit inthis manner is to raise the total pressure in the entire system wherebyan adequate condensing pressure is obtained to insure condensation ofrefrigerant vapor in condenser Hi.

In accordance with my invention I provide an analyzer 33 which isarranged in a compact manner at the vapor expulsion unit 9 and more orless forms a unitary part thereof. The analyzer 33 is formed by thehorizontally extending portion of an L-shaped conduit 3 which is closedat both ends and to one closed end of which is connected the upper endof the inner pipe or passageZG 0f the liquid heat exchanger. Absorptionsolution from the absorber vessel 2! enters one end of the horizontalportion 33 of conduit 34, and the lower end of the vapor lift tube 28 isconnected to the lower closed end of the vertical portion 35 of conduit34 to receive absorption solution to be raised by vapor lift action intothe upper part of the boiler Ill. The boiler I0 is formed by one leg ofan inverted U-shaped conduit whose other leg 33 is connected at itslower end to the analyzer 33 at a region removed from the point at whichthe liquid heat exchanger pipe 26 is connected thereto. .At a regionadjacent to the closed end of the horizontally extending portion 33 ofconduit 34 is connected a conduit 3'! which forms a part of the vaporsupply line leading upwardly from the vapor expulsion unit 9 to thecondenser 14.

- The vapor expulsion unit 9 and absorber including the vessel 2| andcoil 22 form a circuit for absorption solution in the boiler ii) ofwhich a column of liquid is maintained at a height, such as indicated inFig. 1, for example, so that absorption liquid will flow by gravitythrough a connection or tube 33 into the outer pipe or passage 30 of theliquid heat exchanger and conduit 23 into the upper part of the absorbercoil 22. The absorption liquid flowing downwardly by gravity through theabsorber coil 22 passes into the absorber vessel 2! in which theenriched absorption solution is maintained at a level, such as indicatedin Fig. 1, for example. The analyzer or horizontally extending portion33 of the L-shaped conduit 34 is at or slightly below the liquid levelmaintained in the absorber vessel 2!, so that the analyzer will becompletely filled with absorption solution during operation oftherefrigeration system. In effect, the liquid contained in the conduit 34freely communicates with the store of absorption solution in theabsorber vessel 2i through a solid and unbroken liquid body. r

In the operation of the refrigeration system of Fig. 1, vapor generatedin the vapor lift tube 28 and boiler [0 passes from the upper end of theboiler into the conduit 36. The generated vapor usually is a mixture ofrefrigerant vapor and absorption liquid vapor; and, when ammonia andwater are employed as the refrigerant and absorption liquid, forexample, the generated vapor is usually a mixture of ammonia vapor andwater vapor. Due to the difference in boiling points of ammonia andwater, the water vapor may be removed from ammonia by cooling themixture to condense out the water. In Fig. 1 this is accomplished byforcing all of the generated vapor from the conduit 35 through theliquid body in the analyzer 33.

The absorption liquid introduced into the analyzer 33 is relatively richin refrigerant and at a lower temperature than the generated vapor, andin bubbling through the enriched absorption solution the water vapor iscooled suiiiciently and condenses and in this way is removed from theammonia vapor. The latent heat of condensation resulting fromcondensation of water vapor is given up to the enriched absorptionsolution and forms an internally heated zone in which some ammonia vaporis expelled out of solution. Such expelled refrigerant vapor mixes withrefrigerant vapor generated in the vapor lift tube 28 and boiler I3, andthe mixture passes from the analyzer 33 through the conduit 37 to thecondenser [4.

In the embodiment of Fig. 1 it is desirable to keep the generated vaporin direct contact with the absorption solution in the analyzer 33 for arelatively long interval of time. I accomplish this by making thehorizontally extending portion 33 of conduit 34 relatively long in amanner which will not necessitate unduly increasing the overall size ofthe vapor expulsion unit 9. In a practical form of carrying out theembodiment of Fig. 1, the horizontally extending conduit portion 33forming the analyzer can be made as a coil which is disposed about thepipes forming the boiler IE3, heating tube II and vapor lift tube 28, inthe manner shown in Fig. 3 to be described presently. Such coil can beof any suitable length which may vary from three-quarters to one andone-half turns, for example.

It will be observed that the provision of an analyzer in a vaporexpulsion unit 9 like that shown and described lends itself to anextremely compact arrangement of parts. The cluster of vertical pipesforming the vapor expulsion unit occupies a relatively small amount ofspace in which the individual pipes are in the immediate vicinity of oneanother. While the pipes in Fig. 1 are shown in spaced apart relationand in the same plane in order to facilitate an understanding of theinvention, it is to be understood that in a practical embodiment thesepipes may be conveniently spaced apart about the heating tube ll so thatthey will occupy a minimum amount of space. The liquid heat exchanger 27can be made in the form of a coil disposed about the lower parts of theheating tube II and the pipes forming the boiler H3 and vapor lift tube28.

Even when making provision for the analyzer '33 in the vapor expulsionunit 9, there is no greater than that of the liquid heat exchanger,

as seen in Fig. 3. I-Ience, the analyzer 33 in Fig. 1 can beembedded inthe same body of insulatingmaterial which thermallyinsulates the...other D rts of the vapor expulsion unit, in the. manner i shown in Fig.3, thereby providing an efficiently insulated vapor expulsion unit inwhich provision isumade for analyzing generated vapor. especiallyimportant in that the heat recovered in the form-of v latent heat ofcondensation in the analyzer. 33 can be efiiciently utilized and loss ofsuch recovered heat. from the refrigerationsystern-will be minimized.

Essentially; the absorber coil 22 constitutes an externally cooled zonewhile the vapor lift tube 28; and boiler lfleach may be referred to asan externally heated zone of the absorption. liquid circuit. In- Fis. 1it will be seen thattheexternall'y heated zones formed by the vapor lifttube 28gand boiler Ill are vertically extending. and overlap each'otherin: a vertical direction; lhe thermal connections of'hoiler Ill andvapor lift tube 28 to the-heating tube H are formed along linesextending-parallel to the axis of the heating tube, such thermalconnections extending downwardly from a region above the highest pointof the liquid heat exchanger 21. The heat conductive connection of thevapor lift tube as to the heating tube H extends along a verticaldistance of which at least one part is fartherfromv the lower heat inputend of the heating tube ll than the point of the heat conductiveconnection of the boiler IE to the heating tube I! which is nearest tothe lower end of the heating tube.

In the embodiment just described, the relation of the liquid heatexchanger to the pipes of the vapor. expulsion unit and the conduitforming the analyzer-33 is such that any vapor bubbles which may form inthe liquid heat exchanger can freely vent through the connection 38 intothe boiler i 0 and from the liquid heat exchanger pipe 26 into theanalyzer 33. In this way the absorption solution circulation never canbe blocked in the circuit by trapped vapor.

It will also be seen that generated vapor from the conduit 36 passesthrough liquid in the analyzer 33 with practically no liquid head on thevapor. This has certain advantages in that no appreciable resistance tolifting of liquid in the vapor lift tube 28 is developed. This will beapparent when it is considered that the reaction head for lifting liquidin the vapor lift tube: 28 is contained in the vapor expulsion unititself.

and extends downwardly from thellquid level in the analyzer 33, which issubstantially the same as the liquid level in the absorber vessel 2i,

toa level corresponding to aboutthe pointfi atthe lower end of the vaporlifttube 28. In order to obtain efficient lifting of liquid in the vaporlift tube 28 under theseconditions, the externally heated Zone formedvbythe lift tube, is developed as a gas liftpump having a Vapor formingpart or which vapor is produced by heating to effect such lightenins'ofthe fluid columninthe. lift tube that pumping of,

liquid will be promoted under: the. reaction head in, .the Vaporexpulsion unit.

Inthe; embodiment of Fig. 1 the heating tube:

electrical; heating element; In thisway; the uppenxfiarts. ofcthe:boiler; l 0 I WhiOh': do-notcon- This is By forming such a slit til theflow of heat till taln' liquid are not heated to such .a higlr:tenrperature that generated vapor. therein: willdoe;

come-superheated4 By. preventing superheating; of generated vapor, thenormalccondensatiorr of: vapor' in: other parts: of. the; refrigerationsystem.

willlnot'be disturbed.

In the embodimentlofl lisr l thENfi pDI'LIifilETMbBJ 28receives;abSOrptiorrsoliltion which iszrelatively; rich. in refrigerantand which: thereforcmayxbareferred to" as. a; rich liquidv pumpi lin;Fig.1. .25 I have [ShOWll an embodiment of:the,inventions which differsfrom thatof Fig, ly in that, the, vapor lift ,tube therein receivesabsorptionssolue" tion which is relatively weakflin refrigerant-and:

which, may be referred 3 to. asza, WEfitklliQlli-d pulllp those showninFla, l'are; referred to::by the samereference numerals, absorptionsolution; enriched, in refrigerant and flowing from the absorber-:21 lto the vapor expulsion unit 9a passes from the" the same manner as theboiler pipe IB-in Fig. 1 and the lower partorsection Illa. thereof isin.

good thermal contact with theheatinggtube Ila, as by Welding, forexample, as indicatedat- I211..-

To the lower end'of pipe M is connectedthe.

lower end of vapor lift tube 28a which is in; thermal contact with theexterior of the heating.

tube along a line extending upwardly to. the slitv 49a, such thermalcontact in this instance ex?- tending upwardly a greater distancewthanthe.

thermal contact of section I90, of the pipe 4!.

Liquid is raised through vapor lift tube 28a. to the upper part of astandpipe or riser 43- whoselower end is connected to the outer passage.01- pipe Bil of the liquid. heat exchanger 21.- The: heating tube Hain. normal operation heats ;en-= riched absorption solution in the pipesection lila to cause expulsion of refrigerant vapor from solution. Theprincipal part of generated vapor produced in the. vapor expulsion unitof Fis.,. 2 is expelled from solution in pipe section Ilia, and liquidof decreasing, concentration flows downwardlyin, the section Illa to thebottom closedend thereof. In certain. instances it is desirable; toprovide a thermal gap or air space. between the lower portion of thepipe section villa and. the. heating tube Ila. In this wayexcessivenexpulsion of refrigerant vapor from solution in the lower partof pipe section. lila is. prevented. thereby avoiding undesirabledecrease in con centrationof the absorption solution and consequentincrease in its temperature.

A liquid column is maintained in the riser 33 which is at a levelcorresponding" t th liquid level in boiler Iii of Fig. 1, so thatabsorption: solution weak in refrigerant canufiow by gravity. from thelower end of the riser to the upper part. of the absorber coilthroughthe outer. passageill of liquid heat exchangers! and conduit 23..The. plpe ll at a region above the bottom section llla is formed toprovide a. horizontally extending section 33w which is utilized as theanalyzer of the vapor expulsion unit. From the pipe section. silathepipe ll extends upwardly to the. condenser and communicates therewith,such upper: pipe section (tla forming the vapor supply lead-. ingito thecondenser and corresponding; tothe. conduit 37 in Fis. 1.

Vapor expelled from solution in pipe setig In Fig. 2; in; which. partssimilar; ,to;

in which it is analyzed and refrigerant vapor flows through the pipesection 31a to the condenser in which it is liquefied, as explainedabove in connection with Fig. l. The vapor which passes from the upperend of vapor lift tube 28a into the vapor space of riser 43 flowstherefrom through a conduit 45 into the lower part of the horizontallyextending pipe section or analyzer 33a. The vapor entering the analyzer33a from the conduit 45 bubbles through enriched absorption solution andis analyzed, whereby absorption liquid vapor will be removed fromrefrigerant vapor, as explained above in connection with the embodimentof Fig. 1.

In the embodiment of Fig. 2, it will be seen that vapor passing throughconduit 45 is introduced into the analyzer 330; below the liquid surfacelevel of the column of enriched absorption solution therein. While thevapor in conduit 45 and the vapor space of the riser 43 must overcomethe liquid head extending upwardly from the point that conduit 45 isconnected to the analyzer 33a and the resistance to lifting of liquid inthe vapor lift tube 23a is increased, this has not been foundobjectionable and refrigeration systems which have been constructed andembody vapor expulsion units generally like the one illustrated in Fig.2 have been satisfactory in operation.

The embodiment of Fig. 2 possesses certain advantages in that the boilersection iila, analyzer section 33a and vapor supply line can be formedfrom a single continuous length of piping, thereby providing anextremely simple and inexpensive construction. A practical form of vaporexpulsion unit like the one shown in Fig. 2 and just described isillustrated in Fig. 3, in which similar parts are referred to by thesame reference numerals. It will be seen in Fig. 3 that the liquid heatexchanger 2? is in the form of a coil disposed about the pipes extendingdownwardly to the lower part of the vapor expulsion unit, and that theanalyzer 330; is developed as a turn or coil which envelops the vaporexpulsion unit piping. While the pipes are shown as being alongside oneanother, it will be understood that the component parts are distributedas symmetrically as possible about the heating tube i la.

It will be seen that in Figs. 2 and 3 the pipe providing the boilersection Ilia and vapor lift tube 28a and heating tube I la are disposedalongside one another and extend together as a group or cluster in anupward direction to a region at least as high as the upper end of thevapor lift tube 28a. Likewise, in Fig. l the boiler pipe l0, vaporconducting connection 35, vapor lift tube 28 and heating tube H form asimilar group or cluster of pipes and conduits. Further, in bothembodiments of Fig. 1 and of Figs. 2 and 3 the analyzing portions 33 and33a and liquid heat exchangers 21, which are disposed about the heatingtubes I I, essentially form a part of such group or cluster of pipes andconduits serving as component parts of the vapor expulsion unit.

The vapor expulsion unit in its entirety, together with the liquid heatexchanger 27 and analyzer- 33a, are embedded in a single body 45 ofinsulating material retained in a metal shell or casing 41 havingopenings at the top and bottom through which the ends of the heatingtube Ila project.

In vapor expulsion units of the kind shown in Figs. 2 and 3, it isdesirable to develop the units in such manner that they can be tilted toa considerable extent and yet avoid the liquid level in pipe 4| fallingbelow the point 42 at which the l q id exch eer pipe 26,15 connectedthereto. This result is obtained'by arranging the absorber vessel 2| ata relatively high level. However, the absorber vessel 2| should not bearranged at such a high level that the liquid surface level therein issuch a distance above the connecting point of conduit 45 to the analyzer33a to render the vapor lift tube 28a ineffective to lift liquid. Hence,in carrying out the embodiment of Fig. 2 in practice, it will beunderstood that a proper relation of the levels indicated at I, II andIII in Fig. 2 is essential for satisfactory operation.

In view of the foregoing, it will now be understood that a newarrangement for circulating fluids in an absorption refrigeration systemhas been provided which is efiicient in operation, simple inconstruction and inexpensive to manufacture. In the embodimentsdescribed above, generated vapor is analyzed by bubbling such vaporthrough and in counter-flow to enriched absorption solution passing fromthe absorber to the vapor expulsion unit. Hence, generated vapor isanalyzed by passing directly in contact with absorption solutioncirculating in an active part of the solution circuit. By way of exampleand without limitation, the point 42 at which the liquid heat exchangerpipe 26 is connected to pipe 4| may be approximately midway between theliquid level in the absorber vessel 2| and the point at which the vaporconduit 45 is connected to the analyzer or pipe section 33a.

While several embodiments of the invention have been shown anddescribed, it will be apparent that modifications and changes may bemade without departing from the spirit and scope of the invention aspointed out in the following claims.

What is claimed is: r

1. In absorption refrigeration apparatus having a refrigerant vaporsupply line, a circuit for circulation of absorption solution includingan absorber and a vapor expulsion unit comprising an upright heatingtube having a lower heat input end, a vertically extending pipe whichserves as a boiler vessel and is in communication with said vapor supplyline, conduit means for conducting solution from said vapor expulsionunit to the inlet of said absorber including a lift tube having thelower end thereof communicating with the lower part of said pipe, saidpipe and lift tube and heating tube being disposed alongside one anotherand extending together as a group or cluster in an upward direction to aregion at least as high as the upper end of said lift tube, said pipeand lift tube being in thermal relation with the exterior of saidheating tube, conduit means connecting the outlet end of said absorberand said pipe at one level which is intermediate the ends of the latterfor flowing solution by gravity in an unbroken stream from the absorberoutlet through said pipe into the lower end of said lift tube andforming a liquid column in said pipe having a liquid surface above saidone level,

absorber and a vapor expulsion unit comprising an upright heating tube,a first vertically extending conduit which serves as a boiler vessel andis in communication with said vapor supply line, conduit means forconducting solution from said vapor expulsion unit to said absorberincluding a second vertically extending conduit and a lift tube havingthe lower end thereof communicating with the lower part of said firstconduit and the upper end thereof communicating with the upper part ofsaid second conduit, said first and second conduits and lift tube andheating tube being disposed alongside one another and extending togetheras a group or cluster in an upward direction to a region at least ashigh as the upper end of said lift tube, said first conduit and lifttube being in thermal relation with the exterior of said heating tube,conduit means connecting the outlet end of said absorber and said firstconduit at one level which is intermediate the ends of the latter forflowing solution by gravity in an unbroken stream from the absorberoutlet through said first conduit into the lower end of said lift tubeand forming a liquid column in said first conduit having a liquidsurface above said one level, and vapor conducting means to conductvapor from the upper part of said second conduit to a region of saidfirst conduit below said one level and above the connection of said lifttube thereto for flowing vapor in intimate contact and in counterflow toabsorption solution in a part of said first conduit which serves as ananalyzer, said last-mentioned analyzer part of said first conduitessentially forming a part of said group or cluster.

3. In absorption refrigeration apparatus having a refrigerant vaporsupply line, a circuit for circulation of absorption solution includingan absorber and vapor expulsion unit and a vertically extending liquidheat exchanger connected therebetween, said vapor expulsion unitcomprising an upright heating tube having a lower heat input end andpiping in the immediate vicinity of such heating tube comprising aplurality of sections including a first vertical section which serves asa gas lift pump and a second section which is in communication with saidrefrigerant vapor supply line and. to the lower part of which said gaslift pump section is connected, conduit means including said liquid heatexchanger which is disposed about said heating tube and connects theoutlet end of said absorber and said other piping section for flowingsolution in an unbroken stream from the absorber outlet through saidliquid heat exchanger and second piping section into the lower end ofsaid first gas lift pump section and forming a liquid column in saidsecond piping section freely communicating with liquid in the absorber,said first gas lift pump section having a part in which vapor is formedwhich is thermally connected to the exterior of said heating tube in azone extending downwardly below the highest point of said liquid heatexchanger, means including a third piping section for conducting vaporgenerated in said vapor expulsion unit to said second piping section forflowing vapor in intimate contact with enriched absorption solution inan analyzing portion of the second piping section and thereafter to saidrefrigerant vapor supply line and said first and third piping sectionsand heating tube being disposed alongside one another and extending as agroup or cluster in an upward direction to a region at least as high asthe upper end of said first gas lift section, the analyzing portion ofsaid second piping section and said liquid heat exchanger essentiallyforming a part of said group or cluster.

4. In absorption refrigeration apparatus having a refrigerant vaporsupply line, a circuit for circulation of absorption solution includingan absorber and vapor expulsion unit and a vertically extending liquidheat exchanger connected therebetween, said vapor expulsion unitcomprising an upright heating tube having a lower heat input end, avertically extending pipe in thermal relation with said heating tubewhich serves as a boiler vessel and is in communication with said vaporsupply line, conduit means for conducting absorption solution from saidvapor expulsion unit to the inlet of said absorber including said heatexchanger and a vapor lift tube having the lower end thereofcommunicating with the lower part of said pipe, conduit means includingsaid heat exchanger which is disposed about said heating tube andconnects the outlet end of said absorber and said pipe at one levelwhich is intermediate the ends of the latter for flowing solution bygravity in an unbroken stream through said heat exchanger and pipe intothe lower end of said vapor lift tube and forming a liquid column insaid pipe having a liquid surface above said one level, said vapor lifttube having a part thermally connected to the exterior of said heatingtube in a zone extending downwardly below the highest point of said heatexchanger, vapor conducting means including a connection to conductvapor generated in said vapor expulsion unit to a region of said pipebelow said one level and above the connection of said vapor lift tubethereto for flowing vapor in intimate contact with absorption solutionin a part of said pipe which serves as an analyzer, and said pipe andlift tube and vapor conducting connection and heating tube beingdisposed alongside one another and extending together as a group orcluster in an upward direction to a region at least as high as the upperend of said lift tube, the analyzing part of said pipe and said liquidheat exchanger essentially forming a part of said group or cluster.

WILHELM GEORG KoGEL.

REFERENCES CITED The following references are of record in the

